Dead wood

Abstract  The study of behavioural ecology of rare and
elusive species can be challenging, but it is an important
issue for monitoring populations in planning conservation
actions. This is especially true for arboreal insects inhabiting
old-growth forests, whose habits are scarcely known
and rely on many anecdotal data, such as the stag beetle
Lucanus cervus (Linnaeus, 1758). In order to gather information
on daily activity and behaviour of this species, a
radio-telemetry study was conducted in a relict broadleaf
forest surrounded by intensively cultivated land in northern
Italy. During 2014 and 2015, from May to July, 55 stag beetles
(34 males, 21 females) were radio-tagged. Most of them
were caught with the aid of an entomological hand net, but
nine of them were captured by emergence traps set up on deadwood. Visual contact analysis confirmed that stag beetle males were less elusive than females. Males were more frequently radio-tracked in flight, females mostly underground and in proximity of deadwood. Males were mostly observed flying at sunset, and resting or walking on standing trees during the day. The combination of air temperature and humidity determined the optimal weather conditions for male flights (temperature range: 20.7–26 °C, humidity range: 65.5–78.3%). Flying at sunset, mostly performed by males, significantly increased the detectability of the species and supported the selection of the 'transect walk at dusk' as the best monitoring method for the stag beetle.

Dead wood is one of the most important indicators of forest naturalness and the most important manageable habitat for biodiversity in forests. Standing and lying dead wood, and especially coarse woody debris, plays an important part in creating habitats for many highly specialized organisms, e.g., insects, fungi, lichens and bacteria. Temperate mixed deciduous forests, rich in species, have been studied only to a small extent from the point of view of the ecology of wood-related cryptogams. Our study aimed at the reduction of the gap in knowledge about the ecological characteristics of dead wood-dependent organisms by focusing on species of cryptogams developing on various dead wood structures typical of temperate non-beech forests. Studies were performed in forests located in Lithuania, Poland, Belarus and Russia. We recorded 48 species of cryptogams: 18 species of bryophytes, 24 species of fungi and 6 species of lichens developing on dead wood. Our study stresses the importance
of all types of dead wood as a substrate for the development of rare cryptogam species. Logs were the most important substratum type for cryptogams, followed by snags, dead trees and stumps. The cryptogam species richness on logs was several times higher than on the three other types of substrata.
Coarse logs of intermediate decay stages hosted the highest number of cryptogams, followed by freshly fallen logs and, finally, well decayed logs. Assessing the importance of dead wood quality for the studied cryptogams, we found that intermediate decay stages are extremely important for fungi, while bryophytes or lichens do not show a clear preference. The highest number of cryptogams was found on Fraxinus excelsior, Quercus robur and Picea abies, while other tree species had less than half cryptogam species.

Food webs based on dead organic matter have received relatively little research attention. Here we focus on dead-wood-dependent (saproxylic) arthropod communities—an overlooked component of forest biodiversity that contributes to decomposition of fallen trees and nutrient cycling. First, we summarized information on factors that impact saproxylic arthropod biodiversity via a descriptive mini-review of the literature, given that the structure of food webs should be contingent upon local community composition, species richness, and/or species abundances within and among neighboring rotting logs. Next, we coupled intensive fieldwork with molecular approaches to taxonomic identification of saproxylic arthropods sampled from rotting logs in the southern Appalachian Mountains, and synthesized information on their feeding ecology, in order to infer trophic interactions. Our descriptive mini-review highlighted major influences of local-scale (site-specific) factors affecting biodiversity, and by extension, food web structure; a pronounced publication bias toward saproxylic beetles from evergreen forests in Europe was also evident. Our empirical data on community composition of rotting logs at intermediate to late stages of decay revealed a complex food web structure. This comprised internal and external primary nutrient sources (dead wood within logs vs. nearby living trees and fallen leaves), a diverse suite of primary consumers (wood-feeding detritivores, leaf litter-feeding detritivores, as well as herbivores and fungivores), several secondary consumer functional groups (omnivorous scavengers and ectoparasites or parasitoids), and top-level carnivorous predators that were mostly made up of spiders, Opiliones, and centipedes. We close by discussing persistent challenges and limitations, and suggest future research directions.

Over previous decades new environmental measures have been implemented in forestry. In Fennoscandia, forest management practices were modified to set aside conservation areas and to retain trees at final felling. In this study we simulated the long-term effects of set-aside establishment and tree retention practices on the future availability of large trees and dead wood, two forest structures of documented importance to biodiversity conservation. Using a forest decision support system (Heureka), we projected the amounts of these structures over 200 years in two managed north Swedish landscapes, under management scenarios with and without set-asides and tree retention. In line with common best practice, we simulated set-asides covering 5% of the productive area with priority to older stands, as well as ∼5% green-tree retention (solitary trees and forest patches) including high-stump creation at final felling. We found that only tree retention contributed to substantial increases in the future density of large (DBH ≥35 cm) deciduous trees, while both measures made significant contributions to the availability of large conifers. It took more than half a century to observe stronger increases in the densities of large deciduous trees as an effect of tree retention. The mean landscape-scale volumes of hard dead wood fluctuated widely, but the conservation measures yielded values which were, on average over the entire simulation period, about 2.5 times as high as for scenarios without these measures. While the density of large conifers increased with time in the landscape initially dominated by younger forest, best practice conservation measures did not avert a long-term decrease in large conifer density in the landscape initially comprised of more old forest. Our results highlight the needs to adopt a long temporal perspective and to consider initial landscape conditions when evaluating the large-scale effects of conservation measures on forest biodiversity.

Deadwood in various stages of decomposition and diverse spatial arrangements provides habitat for numerous organisms. However, knowledge on the colonization of deadwood by vascular plants in mixed deciduous forest is insufficient. We carried out our study in oak-lime-hornbeam forest in NE Poland. Downed logs were colonized by 49 vascular plant species, a number higher than reported from any other type of forest. Species richness and abundance of plants increased with log diameter and decomposition. The former was higher on broadleaf than on coniferous deadwood (46 vs. 38 species). The frequency and abundance of small-seeded plants (<1 mg) on logs were higher than of bigger/heavier seeded plants. Deadwood surface served probably as an ecological filter, keeping small seeds in cracks, but allowing bigger seeds to roll down. Tree seedling density increased with wood decomposition. However, for eight out of nine species it was higher on the ground than on deadwood. Only spruce seedlings were recorded almost exclusively on deadwood, constituting a crucial substrate for spruce regeneration in meso-eutrophic forests. Therefore, we stress the importance of constant deadwood supply, on the scale of decades, to ensure the diversity of this substrate and to allow the natural dynamics of deadwood-dependent species populations.

Planet Earth is covered by very common Terrestrial (not submersed), Histic (peats) and Aqueous (tidal) humipedons. Beside these typical topsoils there are other more discrete humipedons, generated by the interaction of mineral matter with microorganisms, fungi and small plants (algae, lichens and mosses). In some cases roots and their symbionts can be a driving force of litter biotransformation, in other cases a large amount of decaying wood accommodates particular organisms which interfere with and change the normal process of litter decomposition. Particular microorganisms inhabit submerged sediments or extreme environments and can generate specialised humipedons with grey-black or even astonishingly flashing colours. We describe all these common but still unknown humipedons, defining diagnostic horizons and proposing a first morpho-functional classification, which still has to be improved. At the end of the article, the hypothesis of evolving and interconnected Cosmo, Aero, Hydro, Humi, Co, Litho and Geopedons (related to the microbiota) is formulated as a speculative curiosity.

This study was carried out in the “La Verna” forest, located in the “ForesteCasentinesi, Monte Falterona, Campigna” National Park at the border between Arno and Tevere watersheds. The forest covers an area of 203 ha and it is owned by the Franciscanreligious order. Since 1985 the “La Verna”forest has been managed by the “Casentino”Comunità montana. In 2008 a sector of about 36 ha was selected for an intensive study of the stand structure, and the quality and quantity of coarse woody debris (CWD). A regular networkof 33 sampling point was established. The average stem density was 473 trees ha -1(range 133-1283) and the growing stockof living trees was 657.1 m 3 ha -1 (299-1452.9). The average volume of CWD was 66.9 m 3
ha -1 ranging between 3.7 and 355.8 m 3 ha -1. Of the total volume of dead and living trees, CWDcomprised 10.2%. Among the CWD the volume of logs (66.1%) was greater than thevolume of snags (28.3%) and stumps (5.6%). The study has emphasized that the “La Verna” forest, besides the historical and cultural value, has an important naturalistic value. The past low-intensity silviculture,traditionally applied by the Franciscan monks, has allowed the development of the currentmixed structure and the co-existence in a managed forest of some structural “old-growth”characteristics e.g. the multi-layered vertical structure, the high living biomass and thequantity and quality of CWD.